Attempts are often made to avoid problematic shifting under load at the front chainring. Instead of this shifting under load coverage of as much as possible of the gear spectrum is achieved by means of a correspondingly developed rear multiple sprocket arrangement. A front single chainring together with a high number of eleven or twelve rear sprockets can achieves good coverage. On account of the high number of axially adjacent sprockets on the rear wheel, the width of the multiple sprocket arrangement is certainly enlarged. The chain that meshes with the chainring is also axially secured on the front chainring by means of the axially secured single chainring. On the rear wheel, however, the chain has to overcome a section of several centimeters when shifting from the smallest to the largest sprocket in the axial direction. This increasingly results in the chain running at an angle (also called skew) which has a negative effect on the efficiency, the wear susceptibility, and the noise development of the drive.
Possible solutions which deal with this problem are known from the prior art. Axially displaceable single chainrings which are to adapt to the chain line are thus provided. Different approaches are disclosed in U.S. Pat. No. 6,173,982 B1, US 2013/008282 A1 and DE 10 2015 104 670 A1. The single front chainring is to be displaced on account of the axial forces occurring when the chain is in skew and aligned corresponding to the position of the chain on the rear sprocket arrangement. For this reason, the chainring is mounted so as to be axially displaceable, for example by means of slide bearings or articulations. The problem here is that shifting occurs on the rear multiple sprocket arrangement when there is pressure on the pedals. The chainring meshes with the chain and is under load when there is pressure on the pedals, i.e. the chain is tensioned and presses the chainring against the bearing arrangement. Consequently, the chainring moves axially under the full load of the tensioned drive chain, which frequently leads to the chainring canting at the bearing arrangements and making movement difficult. The axial force acting from the chain onto the chainring is relatively small and is often insufficient to ensure displacement of the chainring.
The prior art also discloses multiple chainring arrangements which include at least one segmented chainring. The chainring segments are not connected together along their ends in the circumferential direction and are consequently movable relatively freely in relation to one another and independently of one another. The segments can be tilted or axially displaced into the chain line by means of a shifting aid, e.g. a cable pull, and thus moved into engagement with the chain. When changing the gear ratio at the front chainring, the chain does therefore not migrate between fixed adjacent chainrings, but, conversely, the chainrings are displaced into the fixed chain line. The goal of said arrangement is to facilitate shifting between the adjacent front chainrings without at the same time changing the chain line. Said approach certainly does not overcome the disadvantages of chain skew which occurs precisely in the case of arrangements with one single front chainring and an increased number of rear sprockets.